1. Field of the Invention
The present invention relates to an optical shaping apparatus and optical shaping method, and particularly, relates to an optical shaping apparatus and optical shaping method whereby high-precision optical shaping can be performed.
2. Description of the Related Art
Heretofore, when employing three-dimensional shape data created with CAD (Computer Aided Design) to create a three-dimensional model, for example, a machining device or the like which is numerically-controlled is employed to create a three-dimensional model by machining.
Also, in recent years, a technique called rapid prototyping (RP) for creating a three-dimensional model without performing machining has caught attention in a great number of manufacturing fields. With rapid prototyping, a manufacturing technique called a layering shaping method is employed wherein cross-sectional shaped thin plates are created by a three-dimensional model being sliced based on the three-dimensional shape data of the three-dimensional model, and the cross-sectional shaped thin plates thereof are layered, thereby creating a three-dimensional model.
Also, according to this technique for creating cross-sectional shaped thin plates, rapid prototyping is classified into optical shaping employing an ultraviolet hardening resin, a method for extrusion-layering thermoplastic resins (FDM), a powder melt adhesion layering method (SLS), a paper thin-film layering method (LOM), a method for discharge-layering powder or hardening catalyst (Ink-Jet method), and so forth.
For example, with optical shaping, the tree-dimensional shape data of a three-dimensional model created by CAD is transformed into STL (Stereo Lithography) which is a format wherein the surface of the three-dimensional model is expressed with a small triangle face, and is input to an optical shaping apparatus.
The optical shaping apparatus generates cross-sectional shape data wherein the three-dimensional model is sliced with a certain interval of, for example, around 0.1 through 0.2 mm, from the three-dimensional shape data, and determines an exposure area of light to be irradiated on the surface of a liquid light hardening resin according to the generated cross-sectional shape data. The optical shaping apparatus irradiates light of the exposure area corresponding to the cross-sectional shape data thereof on the surface of the liquid light hardening resin for each layer of the cross-sectional shape data, and moves a moving trestle within the liquid light hardening resin downward in the vertical direction according to the thickness of the slices of the three-dimensional model. Subsequently, the optical shaping apparatus repeats irradiation of light and movement of the moving trestle from the lowermost layer to the uppermost layer of the cross-sectional shape data, thereby generating a three-dimensional model.
With the optical shaping apparatus, examples of a method for irradiating light on the surface of the light hardening resin include a beam scanning method for scanning an optical beam, an SLM projecting method for employing a spatial light modulator (SLM) such as a liquid crystal panel or the like to irradiate light collectively, and a method for combining the beam scanning method and SLM projecting method.
With the method for combining the beam scanning method and SLM projecting method, a spatial light modulator is employed, an optical beam is scanned along the profile line of cross-sectional shape data after light is irradiated on the exposure areas on the surface of a light hardening resin correctively, whereby a three-dimensional model of which the outline is formed finely over a short amount of time can be shaped.
Now, with Japanese Unexamined Patent Application Publication No. 5-77323, an optical shaping apparatus has been disclosed, whereby a gap between a mirror for scanning an optical beam and the surface of a light hardening resin can be adjusted according to the size of a three-dimensional model.